21011958 has 24 divisors (see below), whose sum is σ = 49665096. Its totient is φ = 6367200.

The previous prime is 21011957. The next prime is 21011959. The reversal of 21011958 is 85911012.

It is an interprime number because it is at equal distance from previous prime (21011957) and next prime (21011959).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52863 + ... + 53258.

It is an arithmetic number, because the mean of its divisors is an integer number (2069379).

Almost surely, 2^21011958 is an apocalyptic number.

21011958 is an abundant number, since it is smaller than the sum of its proper divisors (28653138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21011958 is a wasteful number, since it uses less digits than its factorization.

21011958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106140 (or 106137 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 21011958 is about 4583.8802340375. The cubic root of 21011958 is about 275.9447747099.

The spelling of 21011958 in words is "twenty-one million, eleven thousand, nine hundred fifty-eight".